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MPPT 75/15 Multiple Battery Types

I am installing a Smart Solar MPPT 75/15 on my boat, and will wire it to an AGM battery (Deka 8A4D). My engine starting battery (lead acid Deka 904D). The AGM will power the house loads and the starter battery starts the engine - they have separate positive cable runs. However, when my engine is on or when I am connected to shore power, I combine the positive cable runs so both batteries will charge from the engine or shore. This also means that the Smart Solar charger will now be charging both batteries. Are there settings on the MPPT that will work for this scenario? What are the drawbacks? Or should I not do this at all? (I suppose one work around would be turning off the charge controller when the engine is on, but that's not ideal.)

kyleolmstead asked
spirou commented ·

1 Answer

Cyrix-Li-ct with lead acid house battery

Hi, Just wondering if it is possible or advisable to use the lithium version of the cyrix-ct with a SLA house battery.

Im considering this because adding a lithium house battery soon. I understand I would need to control the BMS wire of the relay to enable the relay to close.

Looks like the enable / disable voltage would work with lead acid being 13.4-13.2v

Thanks, Mike

nzmikec asked
nzmikec answered ·

3 Answers

Overload L1 on VE bus system

I often have that alarm cleared about 30s later. Last time yesterday at 18:47, maybe at the starting time of my washing machine, but not sure. Does not alarm me but I woul like to understand! My setup:

- Off grid, 2kWp on my roof + 23kWh lead batteries.

- 2 solar MPPT 150/65, 1 multiplus 24/5000/230

- BMV712, CCGX

Around the time of alert, exact time to be checked I am normally on my local sun time (UT+28m) but VRM may have some other tim:

  • 17:39: -0.40
  • 17:48: -121.00
  • 18:06 -7.07
  • 18:24 -24.90
  • 18:33 -5.90
  • 18:51 -3.60
  • 19:10 -6.7
  • 19:19 -124.60
  • 19:37 -128.00
  • 19:55 -8.10

Any idea?

Lionel SEYDOUX asked
ejrossouw commented ·

3 Answers

Are my MultiPlus II VE Config charger settings correct for 4 x Omnipower 200Ah batteries?

Just want confirmation on my settings. Help will be appreciated. The ones in bold I'm most worried about.

Stop after excessive bulk checked

Lithium batteries unchecked

Storage mode checked

Use equalization (tubular plate traction battery curve) unchecked

Charge curve Adaptive + BatterySafe

Absorption voltage 57.60 V

Float voltage 54.60 V

Charge current 35 A

Repeated absorption time 1.00 Hr

Repeated absorption interval 7.00 Days

Maximum absorption time 8 Hr

Temperature compensation -72.0 mV/deg

Battery Specsheet: Omnipower-240.pdf

The system is a MultiPlus II 48/3000/35-32 with 4 x OmniPower 240AH batteries as a backup system. I'm using the BMV700 as a battery monitor. Venus GX.

jond asked

0 Answers

Why does charging voltage need to be higher in lower temperatures for lead-acid batteries?

I came across this blog entry which basically says that, for lead acid batteries, lower temperatures require higher charging voltage. Can anyone please explain why this is true, or point to an authoritative source?

I did ask this question on Chemistry SE a while ago, and those guys seem to be of the opposite opinion: higher temps need higher voltage.

Intuitively I disagree with them and agree with the blog post: lower temps need more power to move molecules around, remove sulphate crystals etc. But I seek a definitive authoritative explanation.

Greendrake asked
Daniël Boekel (Victron Energy Staff) commented ·

1 Answer

Charging AGM and lead acid battery simultaneous with Victron Centaur 12/60

I recently bought a preowned boat and i noticed that the charger Centaur charger is connected to AGM consumer battery bank and also the lead acid start battery. Jumper setiting on charger is set to AGM.

Can the AGM charge mode damage the lead acid battery in any way? I just had to replace the start battery (4 years old) as it would not recieve chargning any more and i am wondering if the charger can have anything to do with the short life span.

Mr-T asked
neoneddy answered ·

1 Answer

How to determine the time it will take to charge a battery with an MPPT or PWM charge controller


I am developing a solar battery system to power actuators in remote areas.

I have investigated both MPPT (SmartSolar) and PWM (BlueSolar) charge controllers for this application. I have a few questions concerning exactly how these work and what settings are possible. My objective is to determine how long it will take to charge my chosen batteries with my chosen solar panels.

It is my understanding that the most common effective method for recharging lead acid batteries is to use 3 phases – bulk, absorption and float. In the bulk phase, the maximum amount of current available from the panels is supplied to the batteries. In the absorption phase, a constant voltage is maintained whilst the current is progressively stepped down. Finally, in the float phase, a small current is supplied at a constant voltage to overcome self-discharge. An MPPT charge controller uses a DC-DC converter to match the batteries voltage during the bulk phase, increasing the current to ensure all the power available from the panels is supplied to the batteries. It then uses pulse width modulation to step down the current progressively during the absorption phase. A PWM charge controller supplies the maximum current from the panels during the bulk phase and, like the MPPT charge controller, uses pulse width modulation during the absorption phase. The charge controller switches from the bulk phase to the absorption phase at ~80% fully charged and sets a timer for the absorption phase based on the initial voltage of the battery before charging began. Is this explanation correct?

For lithium ion batteries, it is my understanding that the absorption phase is not required and that they can be charged entirely within the bulk phase with charging ceasing at a set voltage limit. Is this correct?

Finally, in direct reference to the SmartSolar and BlueSolar products, can an output current limit be set? This may be useful in a situation where the recommended charging current of a battery is less than the output current from the solar panel.

Thank you in advance for your advice

ahayes asked
JohnC commented ·

1 Answer

Replacing Lead Acid service battery with Lithium on a boat.

Hi all,

I am currently running on two 100Ah lead acid batteries on my boat. One is solely used for starting the engine and the other one is the "service" battery for all other loads on board. A blue power charger 12V/30A/3 outputs is used to charge both batteries when the boat is connected to shore power. I also have a automatic charging relay to combine batteries during charging, isolate them when discharging and when starting engines. Basically it looks like this:


On top of that I have a SmartSolar MPPT 100/20 charge controller to charge the service battery from a 200W solar array.

I am now looking into replacing the service lead battery with a Lithium battery of the same or double Ah. If I'm not mistaken, the SmartSolar MPPT controller will be able to charge the Lithium battery but I am not sure about the blue power charger. There are multiple scenarios that I'm not sure about:

1. Charging from the engine only (ex. during night time when the solar panel doesn't work).

2. Charging from the engine and the solar panel (ex. when the boat is running during day time).

3. Charging from the solar panel only (ex. when the engine is not running during day time).

4. Charging from the shore power only (ex. when docked during night time).

5. Charging from the shore power and the solar panel (ex. when docked during day time).

Can anyone enlighten me on how I can properly charge both batteries under all possible scenarios?

Thank you in advance,


Nicholas Gouloussis asked
ejrossouw commented ·

1 Answer

Off-grid installation used only during the weekend: best MPPT weekdays configuration


I recently installed the following off-grid system in a country house that will be used only during the weekends:

  • 4 300W solar panels
  • SMARTSOLAR MPPT 150/35 48V
  • 8 Acid Lead batteries of 6V each

Normally I switch on the MP II only when I'm onsite and I need power (once a week so far), during the other days I leave the MP II off. The solar panels and the MPPT are always active (see the screenshot below taken from VEConnect).

I see from the App that every day of the week, even if the MP II is OFF, the batteries are exposed to a charging cycle (bulk, absorption, float). The voltage is raised from 51V to 59V everyday.

That is the behavior suggested from my Victron and battery re-seller.

I'd like to have the confirmation from you that my settings are the best ones in order extend the life of my batteries as much as possible.

Is the daily charging cycle really needed? Wouldn't be better to disconnect the 4 panels during the weekdays and to connect them to the MPPT only during the weekend?

Thanks for your suggestions!


the_salmon asked
Mark answered ·

2 Answers

Coulomb counting in Pb acid battery bank by EasySolar

How does coulomb counting work in an EasySolar inverter when there is no battery monitor and the battery bank is not a Victron product?

Mnoneleli asked
mvader (Victron Energy) answered ·

1 Answer

ESS Dynamic cut off paramters for OPzV Hoppeccke


I need help about the parameters for cut off. The standard values makes that when the Multi draw up to 2500 - 3000w, they stop invert by low battery.

I have 24 cells Hoppecke 6 OPzS 600 that have a capacity:

C10 - 686Ah (1.80v)

C5 - 590Ah (1.77v)

C3 - 510Ah (1.75v)

C1 - 353Ah (1.67V)

I don't know if the voltages values from Hoppecke for each C value is the nominal o the limit when the battery is empty.

Many thanks!


Gurybush asked
mvader (Victron Energy) answered ·

1 Answer

No preset for charging lead calcium batteries with MultiPlus and SmartSolar MPPT?

Hello all.

I've read the manuals and searched the forum and have concluded that the MultiPlus 12/3000 and SmartSolar MPPT chargers do not have specific presets for charging the lead-calcium batteries my yacht will come with. I haven't had the chance to use these chargers with the Victron Connect app via Bluetooth, but would I be right in thinking it will be a simple job to connect and select desired absorption and float voltages, to suit the batteries?

Valden asked
Matthias Lange - DE answered ·

1 Answer

Issues with BULK CHARGE not staying on. MultiPlus 12/2500/120 with Multi Control

Not so new but still good Trojan deep cycle 6 volt large battery bank (12 units),
Charging system:
Solar panels, micro hydro electric,
New Genset Honda 2200W Inverter connected to battery charger.

I can't get the charger to stay on "Bulk charge" like it should. The built in charger kicks off quickly to taper down to float charge way before the battery bank is not even close to be charged. It usually kicks off Bulk charge in about 5 minutes.

  • I keep the multi control setting at 18. (Could it be higher with 2200W genset???)
  • Solar panels/micro hydro seem to charge the battery bank no problem...

Possible causes of charger Bulk charge issues?

  1. My guess is the battery bank is getting old and I need to readjust the settings (INFO PLEASE...)
  2. Wrong charger settings? (INFO PLEASE)
  3. Bad connection? (checked everything)
  4. Faulty temperature sensor? (Checked connection) (Should I disconnect it for test?)

I disconnected the solar panel system and getting the same problem...

Thank you Victron. These units are amazingly durable and well built. This community page is well put together AND HELPFUL (I hope!). I will definitely get a new unit if this one ever gives up...

Patrick, Canada

Blackbox asked
Blackbox commented ·

1 Answer

Is it possible to use a lead acid or OPzS batteries for a grid tie installation with multiplus II?

I'm trying to develop a system where my client uses lead acid batteries or opz to store energy from a grid tie inverter or from the grid at night to store energy and used when need it.

Can a victron system do this? Or does it need a way to control the battery output?

The system that i'm to achieved is similar to the one in the image bellow.


energy_z asked
Rob Duthie commented ·

1 Answer

Replacement for flooded lead acid batteries.

I asked this question over on the whirlpool forum and got some great answers, one of which strongly recommended Victron inverter and BYD batteries. He also suggested I ask the same question here so.....

"I have a 48v stand alone system with 3.6Kw solar, 3.5 kva latronics inverter, Plasmatronics PL60 charge controller and Raylite 1380ah flooded lead acid batteries.

The batteries need replacing.

I have managed to get 13 good years from them so I am happy with that.

But now, with a budget of around AU15 – 16k, what do I do?
I have had companies tell me to throw everything away and start again with a relatively small lithium setup.
I have also been told I can integrate lithium into the current system with significantly smaller capacity.
I have been quoted on several flooded and gel packs all of which seems to be at the upper end of the available budget.

Cycle life seems to be all over the shop depending on who you are asking and each outlet will tell you that their chemistry or construction or configuration is "the only way to go".

The amount of information/misinformation is intimidating and I don't quite know who to believe so I am turning to the well experienced people here to offer there suggestions and reasoning.

The replacement of these batteries is of course, time critical as the gennie is getting a flogging at the moment.

Many thanks in advance,"

moose4621 asked
klim8skeptic commented ·

4 Answers

How do I equalize CPZS Cynetic 1160Ah batteries with an EasySolar 48/5000/70-100 MPPT150/100 Color Control without an external ugly generator? Bluetooth Dongle? No Battery settings display.

Hi folks!

I've had this 48V system running for 4 months now and it works like a charm. It's beautiful to feel like you don't depend on anyone. But that's not true ;). I would hit the equalize button every month until one day I realized that it was not doing it. My setup is in the title plus 24 panels at 230W each mounted in series and parallel as to achieve 100V~130V @ 5 KWH, DC of course. I've tried different firmware versions for the CCGX and updated all devices from VRM. Called my supplier and they said that: This system comes with equalization off by default and that I needed to buy the bluetooth dongle to do this, otherwise I need to have an external generator ( yuck ), in order to activate the equalization. Keep in mind that the "EasySolar" is worth 3,5K. OK. So I need this done NOW so I buy the bootooth wongle and when I head over to, settings/battery, nothing appears. I've tried with different phones and in some of them it detects the MPPT and CCGX and in others it only detects the CCGX, I don't know if that matters because the newer ohone detects the MPPT. I've worked very hard to make this system a reality in my life and I would greatly appreciate if someone with more knowledge that me could help me with this issue, since we all know that equalization is vital in keeping those babies in good health!

Funkaddict asked
Funkaddict commented ·

1 Answer

BSC IP22 12/20 (1) only delivering approx 10 amps


I have just installed a new 300Ah Trojan bank, which was showing around 12.5v on installation. I have attached my charger, but it is only charging at 10amps @ 14.78v.

Is this a limitation of the batteries or of my charger?


JamesL asked
Boekel answered ·

1 Answer

MPPT and BMV712 settings

Please give me feedback on the settings below, do they look ok?

We have Six 6 volt Lead Acid Batteries paired in series totaling 840Ah with the following specs:

*Bulk Charge: Constant current @~10% of C/20 Ah in amps to 2.45+/-0.05 volts per cell (e.g. 7.35 volts +/-0.15 volts per 6 volt battery)

*Absorption Charge: Constant current @~10% of C/20 Ah in amps to 2.45+/-0.05 volts per cell (e.g. 7.35 volts +/-0.15 volts per 6 volt battery) Constant voltage (2.45+/-0.05 vpc) to 3% of C/20 Ah in amps then hold for 2-3 hours and terminate charge Charge termination can be by maximum time (2-4 hr) or dV/dt (4 mv/cell per hour)

*Float Charge (Optional) Constant voltage 2.17 vpc (6.51 volts per 6 volt battery) for unlimited time

*Battery temperature adjustment: reduce the voltage by 0.028 Volts per cell for every 10°F above 80°F, increase by the same amount for temperatures below 80°F.

We have 3 separate 100/30 smart MPPT charge controllers for 3 solar panels, and a BMV 712.

•Current setting on MPPTs:

Absorption: 14.7V max 6 hrs

Float: 13.2V unlimited

Temp. Adjustment: -16.20mV/C

Load output: battery life

Tx port: normal communication

•BMV settings:

Battery capacity: 840Ah

Charged Voltage: 14.3V

Tail current: 4%

Peukert exp: 1.25%

Charge eff: 95%

Current threshold: 0.10mA

Synchronization: on

Do these setting optimize our system? Any feedback is appreciated

Thanks, Caren

Caren asked
Caren commented ·

1 Answer

Will Buck-Boost charger work with Lead Acid L36EFB batteries

I have a motorhome set up with 3 X Yuasa L36EFB Lead acid Batteries. The ideal charge rate for these is 14.4 volts and a max input of 10amps.

I’m starting to “design” a off grid system, using Victron products throughout and eventually want to switch to Lithium batteries.

thanks for any help :)

SteveCounsell asked
SteveCounsell commented ·

1 Answer

Atlas combi with semi-traction batteries

Initially, I want to switch from SLA batteries to LifePO4 ...

Then, after some time and a lot of time spent in blog, navigating, books etc and, after the consciousness that : IF YOU WANT TO SWITCH ... YOU NEED TO CHANGE EVERY THING CORRELATED TO CHARGE (ALTERNATOR, ALTERNATOR REGULATOR, 220 CHARGER, etc.) ... I stay with LEAD batteries !!

But .. but .. if I want to optimize ... I can try the semi-traction batteries (6 volt) that can solve substantially the problem of cost and optimizing the Ah I need.

Here the question : my optimum Victron Atlas Combi 12/1500 (50 Ah max.) may be adjusted to charge a service bank with n.2 semitraction 6volt batteries (in series) of about 250 Ah cadauna (tot. 250 Ah at 12 volt) ?



Adriano asked
Adriano answered ·

2 Answers

Settings for 30/100 MPPT

I have a MPPT 30/100 connected to a pair of 6V Trojan GC-2 lead acid batteries in series. I need the correct settings for the rotary switch. The controller is connected to 4X100W solar cells which are connected as two pairs in series and then those paralleled. Right now the controller only shows a flashing float light. I get 35V checking with a DVM on the cell outputs to the controller

agesilaus asked
JohnC answered ·

2 Answers

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